This invention relates to a socket contact for use in a female connector of paired electrical connectors used in an electronic appliances for connection between two boards.
A hitherto used socket contact will been explained by referring to FIGS. 3A and 3B and FIG. 4. FIG. 3A illustrates in a perspective view an electrical connector 40 using socket contacts of the prior art. FIG. 3B is a perspective view showing the socket contact 42 of the prior art. FIG. 4 is a sectional view of the socket contact 42 of the prior art fixed in the insertion aperture 16 of an insulator 12.
The electrical connector 40 is provided with fitting openings 18 for receiving mating contacts 34 on the opposite side of the connection portions 14 of the socket contacts 42 extending from the electrical connector 40.
In general, the electrical connector 40 mainly consists of an insulator 12 and socket contacts 42 or 421 as well-known. The insulator 12 is an electrically insulating plastic material and formed by the well-known injection molding technique or the like. The socket contact 42 is made of a metal and formed by the well-known press working or the like.
The socket contact 42 consists of three portions, that is, two contact pieces 28 having respective contact portions 32 adapted to contact a mating contact 34, a fixing portion 24 to be fixed to the insulator 12 and a connection portion 14 to be connected to a board 36 or the like. The two contact pieces 28 are arranged in face-to-face parallel relationship for receiving and embracing the mating contact 34 therebetween.
As shown in FIG. 3B the fixing portion 24 is formed with protrusions 26 serving as interference when the socket contact 10 is press-fitted in one direction into the insulator 12. The socket contact 42 is fixed in the insertion aperture 16 of the insulator 12 by press-fitting or the like as shown in FIG. 4. With regard to the relation between the insertion aperture 16 and the socket contact 42, the insertion aperture 16 is about 0.05 to 0.2 mm larger than the socket contact 42 so as to permit the socket contact 42 to be inserted into the insertion aperture 16.
Problems of the socket contact of the prior art will be explained by referring to FIGS. 5 and 6. FIG. 5 illustrates a step of inserting the mating contact 34 into the socket contact 42 fitted in the electrical connector 40 in the state that the connector 40 is mounted on a board 36. FIG. 6 illustrates a step of inserting the mating contact 34 into the socket contact 42 fitted in the electrical connector 40 in the state that the connector 40 is mounted on a board 36, when the fixing portion 24 of the socket contact 42 is too small, even if the clearance between the socket contact 42 and the insertion aperture 16 of the insulator 12 is small.
In the above case, there is clearance of the order of 0.05 to 0.2 mm between the socket contact 42 and the insertion aperture 16 of the insulator 12. Therefore, although there is no problem in the inserting direction, the contact points with the mating contact 34 may be shifted correspondingly to the clearance with respect to directions other than the inserting direction as shown in FIG. 5, as a result of which the stable contact with the mating contact 34 cannot be obtained. What is worse still, if the clearance is too large, there is a possibility of deformation of the socket contact when the mating contact is inserted thereinto. Once the socket contact has been deformed, it becomes necessary to exchange the electrical connector itself and/or the board 36 on which the electrical connector is mounted.
In view of the above fact, it has been proposed to provide clearance as small as possible. However, no matter how an attempt is made, clearance less than 0.05 mm cannot be obtained. In the event that the fixing portion 24 of the socket contact is only 1.7 mm in length as a guide, even if the clearance is less than 0.05 mm, the socket contact would be fixed in an inclined position as shown in FIG. 6, with the result that although there is no problem in the inserting direction, the contact points with the mating contact 34 may be shifted correspondingly to the inclined position with respect to directions other than the inserting direction similarly to the case shown in FIG. 5. Therefore, the stable contact with the mating contact 34 cannot be obtained and there is also a possibility of deformation of the socket contact when the mating contact 34 is inserted thereinto.
With the construction of the socket contact of the prior art, moreover, it is very difficult to bring the connector portion 14 of the socket contact into contact with a land 38 on a board 36, making it impossible to solder the connection portion 14 to the board when the electrical connector is mounted on the board, due to the positional shifting of the socket contact in the insertion aperture 16 of the insulator 12 as described above. The socket contact can be inclined in the insertion aperture as shown is FIG. 5 even if the clearance is of the order of 0.05 to 0.2 mm. Furthermore, it will be understood that once the socket contact has been deformed, there is the need to exchange the electrical connector itself or the board 36 itself on which the electrical connector is mounted.